The present invention is directed generally to a wireless communication device, and, more particularly, to a system and method for controlling backlighting in a wireless communication device.
Wireless communication devices, such as cellular telephones, typically include a keypad and a display. The display may include several lines of alphanumeric characters that provide the user with instructions for operation of the device, feedback in response to user activation of selected buttons on the keypad, and other data display, such as data related to an incoming call.
A common display type uses a liquid crystal display (LCD) because of its low-cost, readability, and low power consumption. A disadvantage of an LCD is that it has poor readability with low ambient light levels. The typical LCD includes a backlight to light the display and thereby enhance readability. The backlight, which is typically an incandescent light, consumes far more electrical power than the LCD itself.
The typical wireless communication device is battery-powered. Conservation of battery power is important to increase the operating duration of the device. Activating the backlight for the LCD display consumes a significant amount of battery power and therefore decreases the operating time of the device. Therefore, it can be appreciated that there is a significant need for wireless communication device that provides backlighting for enhanced readability and conserves battery power. The present invention provides this and other advantages as will be apparent from the following detailed description and accompanying figures.
The present invention is embodied in a system and method for controlling a display light in a wireless communication device. In one embodiment, the system includes a receiver that receives communication signals from a location remote from the receiver. The system also includes a display and a display light that may be selectively enabled by an enable signal. A light controller generates the enable signal based at least in part on signals received by the receiver.
In one embodiment, the receiver receives a time-of-day signal from the remote location and the light controller generates the enable signal based on the time of day. The system may further include a photosensor element to sense ambient light and to generate a signal related to the level of ambient light. In this embodiment, the light controller generates the enable signal based on the time of day and on the level of ambient light. The light controller may generate the enable signal based on the time of day for a first predetermined portion of the day and based on the level of ambient light for the remaining portion of the day.
In another embodiment, the receiver receives positioning signals from the remote location and the light controller generates the enable signals based on the location of the receiver. This embodiment may also include a photosensor element such that the light controller generates the enable signal based on the location of the receiver and on the ambient light.
In yet another alternative embodiment, the light controller may generate the enable signal based solely on the ambient level of light and the signal generated by the photosensor element. If the ambient level of light drops below a predetermined threshold, the light controller may generate the enable signal and ceases generation of the enable signal if the ambient light level is above a second predetermined threshold.